Test instruments such as AC Voltmeters, DC Voltmeters, Ammeters and Ohmeters are all used for measuring the numerical value of their respective functions. All of these measurements and many more are available within one instrument known as a Multimeter or VOM (Volt-Ohmeter). The multimeter can be manually switched between the various functions, usually with a rotary selector knob or push-button switch and displays the numeric value of the function with an analog or digital read-out, and is used in all major sectors of machinery and electronics testing encompassing transportation, communications, computer, control, instrumentation, and components in various electrical circuits and devices. A multimeter also has two receptacles, one labeled (+) and the other labeled (−) into which are plugged two test leads, each lead connecting onto a hand-held probe, to be described below, which is the means of making electrical contact to specific locations on the Device Under Test (DUT). These probes are designed for convenience and safety to insulate and separate the user's fingers away from any electrical contact from the DUT and the multimeter. The probes are in the form of two insulating plastic stems, one held in each hand, each typically about 5-6 inches long and ½ to ¾ of an inch in diameter terminated with either a point-type or clamp-type tip and with a receptacle on each stem to accommodate the plug of a test-wire lead. The two test leads are each a very flexible insulated wire typically about 5 feet long. Most often one lead as well as one probe is colored red to denote positive, and the other lead and probe colored black to denote negative or ground, although other colors may be used. There is a plug on each end of the test lead, one plug plugging-into the receptacle on the stem, the other plug plugging-into a corresponding receptacle on the multimeter.
At the contact end of the probe stem that interfaces with the circuitry of the DUT, different probe tips are required for different test applications. For instance, it is sometimes convenient to have one of the probes tipped (terminated) with an ‘alligator-clamp’, sometimes called ‘clip’, used to clamp the probe to a wire, terminal, or chassis on the DUT (such as a negative, common, or ground) while the second probe tip is a pointed metal rod, called a point or ‘pin’, used to make point contact with locations on the DUT such as the pin-outs of IC chips and on component leads and connections, which require a pointed tip. The alligator clamp of one probe (usually the (−) for DC and ‘ground’ for AC tests) is often clamped in place and that hand can then be removed. Other tests may require both probe tips to be points, or both to be clamps. To meet changing requirements of the test, it is often necessary to change-out one or both of the probes by un-plugging one probe and plugging-in another probe (or probe tips if these are replaceable). The changing to a different tip from that already on the probe, which in practice is often unavailable due to being lost or misplaced, requires two hands, consumes time, and can result in accidents. For example, to avoid the inconvenience of retrieving and installing the appropriate probe or tip, the operator may continue to work with the existing configuration, risking equipment damage or even personal injury.
Consequently, there is a need for electrical test probes where different connector tips (e.g., clamps or points) can be easily deployed with a minimum of experience or practice, without physically replacing the probe or installing a different tip, and using only a thumb movement of the same hand holding the probe without having to subvert the continuity of the test procedure by diverting the eyes away from the DUT to do this.
Some prior patents provide background to the present invention. For example, U.S. Pat. No. 2,522,810 to Bailey discloses an insulated electrical connector comprising a pair of insulated, spring loaded pivoted jaws.
U.S. Pat. No. 2,918,646 describes a convertible test probe adapted for effecting electrical test contact either by clipping, probing, or sliding contact.
U.S. Pat. No. 4,151,462 to Teyler teaches an electrical test probe having a spring biased clip with an extendable and retractable tip movable within the clip. The normally retracted tip is extendible intermediate spring biased jaws of the electrical probe and is retained in the extended position by a spring bias and the gripping action of the jaws. The housing for the probe includes a compartment for containing interchangeable active or passive circuitry operative upon the signal sensed by the probe or a signal injected thereto from the probe. Apparatus for checking the electrical continuity through the probe is also disposed within the housing. A socket which provides both electrical and structural interconnection between the probe and an attached electrical conductor(s) is disposed at the rear of the housing.
U.S. Pat. No. 7,902,848 to Eccleston, et al. discloses a reversible test probe and test probe tip. In one embodiment, a test probe tip is reversible relative to a test probe body. The reversible probe has a first probe tip at a first end and a second probe tip at a second end. The test probe body has an opening operable to receive the first probe tip and the second probe tip. When the first probe tip is positioned in the opening, the first probe tip is electrically coupled to a metal device in the test probe body. When the second probe tip is positioned in the opening, the second probe tip is electrically coupled to a metal device in the test probe body. In another embodiment, a test probe having two test probe tips is reversible relative to a test lead.
The foregoing patents reflect the current state of the art of which the present inventor is aware. Reference to, and discussion of, these patents is intended to aid in discharging Applicant's acknowledged duty of candor in disclosing information that may be relevant to the examination of claims to the present invention. However, it is respectfully submitted that none of the above-indicated patents disclose, teach, suggest, show, or otherwise render obvious, either singly or when considered in combination, the invention described and claimed herein.